What progression is included in the customer service role ? :)

Make sure you get the most from your development time by having regular discussions with your manager. Discuss how best to meet your development goals, track progress by recording your agreed development activity on a development plan.

• everyone gets a minimum of five formal days learning and development; provided through online, face to face or coaching
• covering a range of learning: profession-specific, soft skills, technical skills
• we also have specific targeted development programmes for colleagues looking to progress to the next grade and targeted programmes to help Black, Asian and Minority Ethnic colleagues reach senior roles

Is it possible to switch career roles within hmrc from a customer advisor ? Has this been done before ?

You would need to apply for a different position and be successful within the recruitment process. There are internal temporary opportunities in addition to permanent moves.